Phosphorescent materials have been used in a variety of commercial applications because they have the property of continuing to emit light for an extended period of time after excitation. Phosphorescent pigments have, therefore, been used in warning signs; marking of vital machinery; dial illumination; directional signs on walls of underground stations, garages, hallways; and applied to helmets as used in fire departments, accident prevention, etc. Phosphorescent pigments have also found application for use on protective clothing, sports equipment and a variety of toys where the effect of glowing in the dark provides amusement, ornamental and/or safety features. Phosphorescent materials include a phosphor which has been artificially prepared and has the property of lumincescence when activated by appropriate wavelengths of light. Phosphors may be selected from the group of zinc sulfide, zinc cadmium sulfide, alkaline earth sulfides with or without a trace of activators, such as silver, copper or manganese. The phosphorescent pigments may be incorporated into a variety of carriers so that the phosphorescent material may be used in many ways such as forming heat transfers to fabric surfaces for purposes of ornamentation, such as disclosed in U.S. Pat. No. 4,089,722. Such luminescent materials have also been used to aid in the writing and reading in the dark, such as disclosed in U.S. Pat. Nos. 2,632,116, 2,883,770, 3,832,556 and 3,978,340. These systems all contemplate in one manner or another the activation of the phosphorescent material to provide illumination of the material on which normal writing by pencil or pen is achieved.
U.S. Pat. No. 2,516,727 discloses the use of phosphorescent material, selected areas of which are exposed to activating light. By the use of various shaped figures positioned on the phosphorescent material, silhouette or shadows remain which are not illuminated. However, this patent does not contemplate any form of device which ensures that the phosphorescent material is deactivated before the desired images are formed, thus rendering it useless for transport of the light chargeable pad in illuminated areas and subsequent immediate use in dark areas.